<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #header{
        width:100%;
        height:100px;
        background-color:red;
        }
        #footer{
        width:100%;
        height:100px;
        background-color:blue;
        }
    </style>
</head>
<body>
<div id="header">header</div>
<div id="main">
{% block main %}

{% endblock main %}
</div>

<div id="footer">footer</div>
</div>
</body>
</html>